Acoustic device



Feb. 7, 1933,

J. G. FLINT ET AL ACOUSTIC DEVICE Filed March 29, 1930 Has".

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INVENTUHS' 0 a MGKIE W w 61M ATTORNEY Patented F 7, 1933 UNITED STATES PATENT OFFICE -JAMES G. FLINT AND DAVID G. MCKIE, OF ALDWYCH, LONDON, ENGLAND, ASSIGNOBS I'O mil-KEN ELECTRIC COMPANY, BATION OF NEW YORK INCORPORATED, OF NEW YORK, N. Y A. OOBPO- acousrrc navrca Application filed March 29,

This invention relates to acoustic instru-' ments and more particularly to improvements in the arrangements for damping the vibrations of the diaphragms of such instruments.

Difiiculties have been experienced in finding a satisfactory damping arrangement for such diaphragms due to the fact that the material employed for damping purposes was often liable to slip off the seating provided in the acoustic instrument. Such difficulties were particularly apparent when a damping arrangement consisting of a pile of paper or like leaves was employed and the invention is therefore particularly though not exclusively applicable to acoustic instruments employing a damping arrangement of this type.

According to the invention there is provided in combination with a pile of paper or like leaves comprising a damping arrangement for the diaphragm of an acoustic instrument, a retaining device embracing the pile in such manner as to prevent displacement of the leaves in a lateral direction while permittingproper damping action of the pile.

The invention is particularly applicable to telephone transmitters employing some method of damping the diaphragm, and provides means for positively maintaining the damping material in position on the transmitter capsule.

1 other suitable material and the flexib This means preferably comprises a flexible cap which fits over the damping material in such a way as to hold it imposition on a seating forming part of the transmitter capsule. The most convenient damping material 0on sists of a pluralityof thin rings of pa r or e cap mayjhen be constructed in such a way that the top of the cap is of annular formation so as to cover the paper rings, while the sides of the cap extend. over the seatin of the damping material thereby holding t e latter in position.

e The invention will be more completely un derstood from the following detailed description which is given in conjunction with the accompanying drawing in which Fig. 1 illustrates a sectional side view of a telephone transmitter ca sule showing the damping material of the phragm held in posidamping arrangement for the dis.

1980, Serial No. 439,932, and in Great Britain October 30, 18*.

tion by a cap in accordance with the invent on, and Fig. 2 illustrates in perspective a flexible cap such as is employed for holding the damping material in position.

Referring now to the drawing the framework 1 of the transmitter capsule is shown in Fig. 1 with a diaphragm 2 held in position by means of a clampin ring 3 which is spun over the periphery o the diaphragm and the edges of the framework 1. Clamped to the framework 1 by means of a nut and bolt 5 and 6 is an electrode carrier 4 having a raised portion 4a at its periphery which forms a granule chamber and also acts as a seating for the damping material 7 which is interposed between the electrode carrier 4 and'the diaphragm 2 and in the arrangement shown comprises a pluralit of paper rings. The back electrode 8 whlch usually consists of a carbon plate is shown in section. Interposed between the damping material 7 and the diaphragm 2 is a flexible cap 9 which is shown detached from the rest of the apparatus in Fig. 2. This cap is constructed of any suitable flexible material such as silk impregnated with cellulose acetate and is preferably constructed in such a way that the top of the cap forms a ring of approximately the same external and internal diameters as those of the damping rings and the sides of the cap are arranged to cover the edges of the damping rings 7 and to extend over the portions of the electrode carrier 4 which act as a seating for the dampingrings. It will thus be seen that when the cap 9 is placed in position it will hold the damping rings in position on the electrode carrier and will prevent their lateral move- "ment either with respect to the electrode carrier or with respect to each other. F urthermore since the cap is constructed of flexible material it will not interfere with the damp ing of the diaphragm even though it is interposed between the diaphragm and the actual damping material.

What is claimed is: 1. The. combination of a sea surface with a pile of paper tmg leaves wmfigsing a of an acoustic instrument, and a sli able cover of flexible material embracing the pile and seating surface in such manner as to prevent displacement of the leaves from said seating surface in a lateral direction while permitting proper damping action of the pile.

2. In a telephone transmitter the combination with a plurality of damping rings interposed between the diaphragm and the granule chamber casing of a cap for retainmg said rings in position.

3. A damping arrangement for a diaphragm of a telephone transmitter having a receptacle provided with a seating surface, damping material on said surface, and a flexible cap fitting over said damping material and extending beyond the seating surface.

4. A damping arrangement for a telephone transmitter comprising a diaphragm and a chamber for carbon granules, consisting of a pile of thin leaves, and, an annular cupshaped member between said diaphragm and said leaves and having a portion slidably extending along the outer surface of said chamber for holding said leaves in position.

5. A damping arrangement in accordance with claim 4 in which said cup-shaped member is composed of silk impregnated with cellulose acetate.

In witness whereof, we hereunto sign our names this sixth day of March, 1930.

- JAMES G. FLINT. DAVID G. MoKIE. 

